C语言实现将彩色bmp图像转化为灰图、灰度图像反色

本文实例为大家分享了c语言实现将彩色bmp图像转化为灰图、灰度图像反色的具体代码，供大家参考，具体内容如下

彩色图像转灰度图像

彩色（24位）bmp图像结构：

typedef struct{
 bitmapfileheader bfheader;
 bitmapinfoheader biheader;
 unsigned char *imgdata;
}bmp;

灰度（8位）bmp图像结构：

typedef struct{
 bitmapfileheader bfheader;
 bitmapinfoheader biheader;
 rgbquad palette[256];
 unsigned char *imgdata;
}bmp;

bmp灰度图像比彩色图像多了一个调色板，调色板中每个元素的类型是一个rgbquad结构，占四个字节，其定义如下：

typedef struct{
 unsigned char rgbblue;
 unsigned char rgbgreen;
 unsigned char rgbred;
 unsigned char rgbreserved;

}rgbquad;

在实际的bmp图像中调色板：

代码实现将彩色bmp图像转化位灰值图像：

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#pragma pack(1)   //全紧凑模式

typedef struct {
 unsigned char bftype[2];
 unsigned int bfsize;
 unsigned short bfreserved1;
 unsigned short bfreserved2;
 unsigned int bfoffbits;
}bitmapfileheader;

typedef struct {
 unsigned int bisize;
 unsigned int biwidth;
 unsigned int biheight;
 unsigned short biplanes;
 unsigned short bibitcount;
 unsigned int bicompression;
 unsigned int bisizeimage;
 unsigned int bixpixpermeter;
 unsigned int biypixpermeter;
 unsigned int biclrused;
 unsigned int biclrimportant;
}bitmapinfoheader;


typedef struct{
 unsigned char rgbblue;
 unsigned char rgbgreen;
 unsigned char rgbred;
 unsigned char rgbreserved;

}rgbquad;

typedef struct{
 bitmapfileheader bfheader;
 bitmapinfoheader biheader;
 rgbquad palette[256];
 unsigned char *imgdata;
}bmp;

int main(){
 file *fp;
 if((fp=fopen("d:\temp\\test.bmp","rb"))==null){
  perror("can not open file!");
  return -1;
 }
 //读入彩色bmp图像文件头，信息头和图像数据
 bitmapfileheader bfheader;
 fread(&bfheader,14,1,fp);
 bitmapinfoheader biheader;
 fread(&biheader,40,1,fp);
 int imsize=biheader.bisizeimage;
 int width=biheader.biwidth;
 int height=biheader.biheight;
 int bitcount=biheader.bibitcount;
 int linebytes=(width*bitcount+31)/32*4;
 
 fseek(fp,bfheader.bfoffbits,seek_set);
 unsigned char*imagedata=(unsigned char*)malloc(imsize*sizeof(unsigned char));
 fread(imagedata,imsize*sizeof(unsigned char),1,fp); 
 fclose(fp);

 bmp b;
 int i,j,k;
 memcpy(&(b.bfheader),&bfheader,sizeof(bfheader));
 memcpy(&(b.biheader),&biheader,sizeof(biheader));
 b.bfheader.bfoffbits=1078;  //因新增了调色板，需调整图像数据偏移位置
 b.biheader.bibitcount=8;  //改变图像位数
 int linebytes_new=(width*8+31)/32*4; //重新计算每行数据字节
 b.biheader.bisizeimage=linebytes_new*height; //改变图像数据大小
 b.bfheader.bfsize=1078+b.biheader.bisizeimage; //改变文件数据大小
 b.imgdata=(unsigned char*)malloc(sizeof(unsigned char)*b.biheader.bisizeimage);
 memset(b.imgdata,0,sizeof(unsigned char)*b.biheader.bisizeimage);
 for(i=0;i<256;i++){
  b.palette[i].rgbblue=i;
  b.palette[i].rgbgreen=i;
  b.palette[i].rgbred=i;
 }
 
 for(i=0;i<height;i++){
  for(j=0;j<width;j++){
   //将每一个像素都按公式y=b*0.299+g*0.587+r*0.114进行转化
   b.imgdata[linebytes_new*i+j]=imagedata[linebytes*i+j*3]*0.299+imagedata[linebytes*i+j*3+1]*0.587+imagedata[linebytes*i+j*3+2]*0.114;
  }
 }

 char savepath[]="d:\temp\\save_test.bmp";
 file *f=fopen(savepath,"wb");
 if(f==null){
  perror("can not open file!");
  return -2;
 }
 fwrite(&b.bfheader,sizeof(bitmapfileheader),1,f);
 fwrite(&b.biheader,sizeof(bitmapinfoheader),1,f);
 fwrite(&b.palette,1024,1,f);
 fwrite(b.imgdata,sizeof(unsigned char)*b.biheader.bisizeimage,1,f);
 fclose(f);
 
 free(imagedata);
 free(b.imgdata);
 return 0;
}

代码效果：

灰度图像反色

int i,j;
 for(i=0;i<height;i++){
  for(j=0;j<width;j++){
   b.imgdata[linebytes*i+j]=255-imagedata[linebytes*i+j];
  }
 }

代码效果：

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